Electret microphones have been used for almost half a century since their introduction in 1962. The microphone itself has a very high output impedance due to the capacitance of the electret material. In order to overcome this problem, a junction gate field-effect transistor (JFET) or a complementary metal-oxide semiconductor (CMOS) buffer transistor is integrated within the microphone capsule to change the output impedance. The traditional way to capture the electrical output from these microphones has been to measure the voltage across the microphone, amplify the voltage and then digitize it inside a codec.